Ultraviolet light (UV) can be used to disinfect fluids, such as water. Exposure to ultraviolet light is believed to detrimentally alter the genetic (DNA) material in cells, thereby reducing the population of potentially pathogenic microorganisms such as bacteria, viruses, molds, algae and the like. Typically, water flows past UV lamps in UV disinfection systems thereby exposing microorganisms in the water to a lethal dose of UV energy. Typical water disinfection systems and devices emit UV light at approximately 254 nm, which is believed to penetrate the outer cell membrane of microorganisms, pass through the cell body, reach the DNA and alter the genetic material of the microorganism.
Water purification systems often comprise a source of germicidal UV radiation configured and positioned to irradiate a water sample to be purified. The water sample can be contained in a conduit or chamber of any suitable shape and material to permit exposure of the water to a desired amount of the germicidal UV radiation. For instance, a UV radiation source can be placed adjacent to, or within, a water-containing conduit or chamber. A UV reflective surface can be positioned to reflect UV radiation back toward the water to be purified, to enhance the level of UV radiation within the water sample or to make more efficient use of the UV radiation generated by the source of UV radiation. For example, published U.S. Patent application US 2004/0004044A1, filed Jul. 3, 2002 and published Jan. 8, 2004, and U.S. Pat. No. 5,141,636, filed Jan. 8, 1991, disclose the use of a reflective material such as aluminum foil to reflect UV radiation toward water to be purified. What is needed are compositions to provide a desired level of UV reflectance for use in water treatment systems. Preferably, such compositions are also suitable for direct contact with water to be purified.